A naturally-occuring radioactive gas, called radon, may be lurking in your home. According to the World Health Organization, radon is the second leading cause of lung cancer. But a few scientists suggest that it may also have a therapeutic side.
You cannot see it, taste it or smell it, but radon has the potential to kill you - or cure you.
Radon is what scientists call a noble gas, which simply means it does not react with anything. What it does by itself, is another matter. Uranium decay produces radon, which breaks down into even smaller radioactive particles, and releases energy in the process. If people breathe radon gas, this radioactive decay takes place in their lungs.
Studies on uranium miners link radon with lung cancer, especially when coupled with smoking. Scientists believe that radon provides a similar danger when it seeps into homes from underground.
Johns Hopkins University physician Jonathan Samet has compiled research on indoor radon.
"There is now actually a large body of evidence where people have gone directly to the general population, and looked to see what the risks of indoor radon are," he says. "Those studies show that the risks indoors are basically what was estimated when we said, 'What if the risks for miners extended down to these lower levels?'"
Because of this, the World Health Organization has launched the International Radon Project to lower in-home exposure to radon. Organization researcher Hajo Zeeb explains.
"It does increase the risk of lung cancer. This is what we know nowadays quite clearly, so there is quite a reason to diminish this risk of radon in houses all over the world," Dr. Zeeb says.
Dr. Zeeb says the World Health Organization plans to collect scientific research and encourage public awareness of the dangers posed by this gas. Radon test kits are fairly inexpensive, and if the gas is discovered, there are numerous ways of venting it from homes.
But many people believe radon has benefits. They claim that radon therapy can work miracles. At spas in Austria, patients can soak in radon-rich hot springs, a treatment covered by some European health insurance companies.
Converted mines in Montana offer similar services. The owner of one, Patricia Lewis of the Free Enterprise Radon Health Mine, says she has witnessed radon's restorative power:
"People have relief with pain. Auto-immune disorders respond," Ms. Lewis says. "Those include lupus, MS [multiple sclerosis], migraines [headaches], arthritis of all kinds, prostate [disorders], gout, fibromyalgia [muscle pain and fatigue] and associated symptoms. That's what we see here."
Most scientists are skeptical about such therapy, but a theory called hormesis lends support to Ms. Lewis' claims. Hormesis suggests that small amounts of a normally dangerous chemical may actually stimulate healing.
This idea was tested in a study five-years ago in the journal of the British Society for Rheumatology. In it, half a group of patients with rheumatoid arthritis soaked in radon spas, and half bathed in spas without the gas. Although both groups felt better initially, only the radon group felt lasting effects.
But the National Research Council, a science advisory board to the U.S. government, says the benefits of radon do not outweigh the dangers. In a June report, the council concluded that the preponderance of scientific evidence suggests there is no safe dose of any type of radiation. But, they also admitted it is hard to get accurate data with such small amounts.
Ms. Lewis and other supporters of the hormesis theory point out that new research could change things, but Dr. Zeeb says that is unlikely.
"Low doses are difficult to study in scientific studies, but there is no reason to believe that we have to take a different view on this, apart from knowing that ionizing radiation is a carcinogenic agent at any dose," Dr. Zeeb says.
For now, the World Health Organization advises everyone to test their homes for radon.